Method of making sheet metal can bodies



A. L. KRONQUEST METHOD OF MAKING SHEET METAL CAN BODIES Original FiledMay 3, 1935 'F HQ.

Patented Aug. 3, 1937 METHOD OF MAKING SHEET METAL CAN BODIES AlfredI... Kronquest, Syracuse, N. Y., asaignor to Continental Can Company;Inc., New York. N. Y.,, a corporation of New York Original applicationMay 3, 1935, Serial No. 19,117, now Patent No. 2,083,452, dated JuneDivided and this application October 28, 1935, Serial No. 47,183

1 Claim. (01. 113-120) The invention relates to new and usefulimprovements in the method of making a sheet metal can body. It is acommon practice in making a sheet metal can body to shape the metalblank from which the can body is to be formed so as to provide a sideseam having lapping sections at the ends thereof and interlocking hooksextending from one lapping section to the other.

- The interlocked hooks are bumped and then molten solder is applied tothe side seam for solder bonding the same. Considerable diillculty hasbeen experienced in the solder bonding of the interfolded parts of theside seam due to the trapping of the heated gases which prevents thesolder from flowing by capillary attraction to the extreme limits of theside seam.

An object of the present invention is to provide a method of forming theside seam of a can body which will permit the solder to flow bycapillary attraction throughout the entire limits of the side seam.

In the drawing- Figure 1 is a plan view of a sheet metal blank shapedfor forming a can body, which blank is constructed so as to aid in thesolder bonding of the interengaging hooks forming the side seam;

Fig.2 is a view showing the hooks formed on the blank prior to theinterengaging of the same; v

Fig. 3 is a view showing the hooks united and bumped ready for solderbonding;

Fig. 4 is a sectional view on an enlarged scale on the line 4-4 of Fig.3;

Fig. 5 is a similar view'after the solder bond has been applied thereto,and

Fig. 6 is a longitudinal sectional view through the side seam on anexaggerated enlarged scale showing the curving of the side seam duringsolder bonding.

In carrying out the invention, a sheet of metal is cut so as to providea body blank which is indicated at l in the drawing. This body blank isnotched at 2, 2, so as to form an offset portion 3 which is bent back toform a hook indicated in dotted lines at 4 in Fig. 2 of the drawing. Theother edge portion of the body blank I is provided with slits 5, 5offsetting a portion 6 which is bent back to form a hook indicated at lin Fig. 2 of the drawing.

The body blank is also provided with slits 8, i. There are a series ofthese slits, and they are comparatively closely spaced and disposedthroughout a considerable portion or the length of the ofiset portion 5forming the hook 'I. These slits extend, as shown in the drawing, at anangle to the edge of the metal and preferably at an angle of aboutforty-five degrees. The slits terminate onthe line a, a which is theextreme limits of the side seam. In other words, the line a, a issubstantially beneath the edge of the inturned hook I as shown in Fig. 2of the drawing. After the blank is shaped, it maybe curved at once intothe cylindrical body form and the edge portions turned back to form thehooks, but preferably the edge portions are'turned back to form thehooks 4 and i first, after which the blank is formed into. cylindricalshape. The hooks 4 and l are interlocked in the usual way and thenbumped. This completes the can body ready'for solder bonding.

In Fig. 4 of the drawing, there is shown on an enlarged scale a sectionalong one of the slits in the side seam. It will be noted that the slit8 extends to the point 9 which is substantially the limit of the sideseam. In the applying of a solder bond to the side seam, the metalthroughout the region of the side seamis heated and the heating of themetal incident to the solder bonding will cause the side seam of the canbody to curve inwardly as indicated in Fig. 6. The reason for this isthat the heat is applied to the can body in the region of the side seamonly. The slitting of the edge portion of the metal throughout theentire region of the hook 1 provides spacesbetween the cut edges throughwhich heated gases may escape.- The curving of theside seam tends toseparate the edges along the slit. For solder bonding the side seam,solder is applied to the outer surface of the side seam as indicated atill in Fig. 5 of the drawing. The molten solder will flow by capillaryattraction between the contacting metal parts. Any gases formed inadvance of the flowing solder will pass out between the side walls ofthe slits and this will allow a free flowing of the solder by capillaryattraction along the contacting surfaces between the hook 4 and theinner portion of the can body underlying the hook I. Thesolder will alsoflow around the end of the hook 4 and along the inner face of the hook Iand the under face of the hook 4. Here again, any gases accumulatedahead of this flowing solder will escape through the spaces between theedges of the slit 8. The solder will continue to flow along the outerface of the hook I and the inner face of the body to the extreme outerlimits of the side seam as indicated at H. It is extremely importantthat the solder bond shall extend to this outer limit I, for the reasonthat when the seam it is because the solder bond between the outer faceof the hook I and the can body wall is ruptured. When the interlockedhooks are solder bonded without forming slits such as described, thegases are likely to be trapped in the interfolded parts of the metal andthe solder will not flow all the way to the extreme limit indicated atII. This makes a weak solder bonding which is liable to be rupturedunder strain due to internal pressure within the container. With theslits formed, however, as described above I am able to produce a solderbond for a lock seam can body which is substantially uniform all the wayto the extreme limits of the. contacting metal portions forming the sideseam.

As noted above, the slits are preferably formed at an acute angle to theedge of the side seam. The slit extends from the free edge of the hookto the limits of the side seam, and therefore, it extends around intothe body of the can and across the portion thereof which is directlybeneath the hook. When the hook is turned back the slit in the hookportion will extend at an angle to that portion of the slit runningaround into the body portion. In other words, the slit in the hook isout of alinement with the slit .in the body portion. The slit, in ameasure, extends along the side seam and permits the gases to escapetherethrough at different points lengthwise of 'the side seam.Furthermore, when the side seam is solder bonded, the solder unites theedges of the slits and this solder bond joining the edges extends alongthe side seam so that one part is not directly over another. The lateralstrain on the side seam when the container is subjectedtointernalpressure will be distributed along this solder bond, joining theedges, and therefore, the slitting of the edge does not, in any way,weaken the side seam.

It is stated that the slits are closely spaced. They are spacedsufliciently close together so as to prevent the trapping of the gasesbetween the same and to insure a continuous solder bond between theouter face of the hook I and the body wall beneath the same throughoutthe entire length of the side seam. The solder bonding is usuallyapplied by a roll running in a bath of molten solder. The solder willflow freely between the contacting walls at the ends of the hooks wherethe gases are free to escape, and it is in the central region of theside seam where the gases are likely to be trapped so as to pre ventproper solder bonding. Therefore, the slits are disposed in the centralportion of the side seam, and it is not necessary to provide slits inthe edge portions of the blank in the region immediately adjacent theends of the hooks.

From the above it will be apparent that a new method of forming a lockand lap seam can body has been provided wherein a more efllcient solderbonding can be accomplished throughout the entire extent of the sideseam. The first step in the method consists in the shaping of the blankand the slitting of the edge portion which is to form the inner hook.The hooks are then formed in the usual manner and interlocked and bumpedand the solder applied thereto. During the preheating or the side seamand the application of the molten solder thereto, the slits formed inthe inner partsgof the side seam will provide spaces allowing theforming gases, due to the heating of the flux, to escape and permit thesolder to flow freely by capillary attraction to the extreme limits ofthe contacting metal parts forming the side seam.

The can body produced by the above-described method forms no part of thepresent invention, but is shown, described and claimed in a copendingapplication filed May 3, 1935, Serial Number 19,717, now Patent #2083352which this application is a division.

It is obvious that changes in the details of construction and the methodof carrying out the invention may be made without departing from thespirit of the invention as setjorth' in the appended claim.

Having thus described the invention, what I claim as new and desire tosecure by Letters- Patent, is-

The method of making a sheet metal can body consisting in shaping ablank from which the can body is to be formed so as to provide a sideseam having interlocking hooks, cutting the edge portion of the blankthat is to form the inner hook of the side seam along parallel linesspaced from each other so as to form slits extending from the edge ofthe blank at an acute angle thereto to substantially the full limits ofthe side seam, bending the edge portions of the blank to form the hooks,and interlocking said hooks and bumping the same, preheating the sideseam and

